In order to protect rice seeds or seedling from diseases caused by fungi or bacteria, intact rice seeds in the husk are conventionally soaked in a solution of one or more fungicidal and/or bactericidal agents before sowed. However, this process can not fully prevent diseases caused by fungi or bacteria. Moreover, this process has a pollution problem caused by discharge of the solution of the fungicidal and/or bactericidal agent after seed soaking as well as an economical problem by loss of the fungicidal or bactericidal agent. Furthermore, in order to completely prevent damage caused by the fungi after sowing, the fungicidal agent is needed to be applied again after sowing. Also in order to prevent damage by insects after sowing, the sprinkling of the insecticidal agent is needed.
Coating intact rice seeds with a fungicidal or bactericidal agent was performed for the purpose of solving the above-mentioned problems. However, this could not sufficiently solve the problems.
Beside, in order to germinate intact rice seeds, it is necessary to have the seeds first absorb enough water. Thus, intact rice seeds need to be kept under water for a considerable time period to absorb enough water through the husk before sowing so as to attain uniform sprouting, because the outside of the seeds is covered by the husk.
In the conventional technology, intact rice seeds with husk are coated, on the husk, with a binder which contains an agricultural chemical, and are soaked in water containing one or more fungicidal or bactericidal agents for about one day to sterilize adhering fungi or bacteria. Subsequently, the water containing the fungicidal or bactericidal agents is replaced with fresh water. Then, one waits for development of the sprout of rice seeds, while circulating optionally heated water through the mass of rice seeds.
Rice seeds usually start sprouting and developing the coleoptile of the embryo in about three days after the start of circulation of water, and come into a so-called “pigeon breast” state. The rice seeds in the pigeon breast state are sown on soil in a tray, and reared in a dark place for three to seven days. Although radicles come out in this period of time, the leave which have first been developed grow further, so that the seedlings have much better developed leaves, compared to the development of the radicles.
Then the rice seeds in this developed state of sprout growth are moved together with the tray from the dark place to a place with light such as a greenhouse and allowed to grow according to the conventional method.
However, in this method, a considerable time of soaking in water is required before sprouting; the sprouted rice seeds generally show non-uniform growth and tend to fall sick; and furthermore, the water containing the fungicidal or bactericidal agent used in the sprouting process is discarded to cause a pollution problem and a loss of the fungicidal or bactericidal agent.
In addition, the radicles which just came out of the rice seeds in this method are comparatively weak to chemical toxicity of an insecticidal agent. If an insecticidal agent is used when the radicles are still small, growth of the radicles is arrested by the toxicity so that growth of rice seedlings is slow. Accordingly, an insecticidal agent can be used only after considerable development of the radicles. Then, the sprouted rice might be eaten by insects.